The present invention relates to a motor apparatus having a clutch for coupling a rotary shaft of the motor apparatus to a worm shaft.
Japanese Laid-Open Patent Publication No. 2003-278784 discloses a motor apparatus incorporated in a vehicle power window apparatus. As shown in FIG. 10A, if a motor main body 102 of the motor apparatus rotates a rotary shaft 101, a rotation of the rotary shaft 101 is transmitted to a worm shaft 103 of a deceleration portion 104 through a clutch 105.
As shown in FIG. 10B, the rotary shaft 101 rotates a drive rotor 111 in the clutch 105. If the drive rotor 111 rotates a driven rotor 112, the worm shaft 103 is rotated.
However, the clutch 105 prevents the rotation of the worm shaft 103 from being transmitted to the rotary shaft 101. In other words, if the worm shaft 103 intends to rotate in a state in which the rotary shaft 101 is stopped, the driven rotor 112 is engaged with a cylindrical collar 114 by a roller 115. In other words, a control surface 112a in the driven rotor 112 and an inner circumferential surface 114a of the collar 114 hold the roller 115. The collar 114 is fixed to a gear housing 113 in the deceleration portion 104. Accordingly, the driven rotor 112 cannot rotate, and the rotary shaft 101 does not rotate. A Hall element 121 attached to the gear housing 113 detects the rotation of the rotary shaft 101 by detecting an annular sensor magnet 122 fitted to an outer periphery of the drive rotor 111. A buffering member 123 made of an elastomer resin is arranged between the rotary shaft 101 and the drive rotor 111.
As shown in FIG. 10B, a coupling portion 101a extending from a distal end of the rotary shaft 101 is loosely fitted to a coupling hole 111a of the drive rotor 111. Accordingly, even if the drive rotor 111 is deviated from the rotary shaft 101 due to an assembly error of each of parts of the motor apparatus, an increase of a load in a radial direction applied to the drive rotor 111 and the rotary shaft 101 is suppressed. Accordingly, noise and vibration generated from the motor apparatus under rotation is suppressed. The description “the drive rotor 111 is axially deviated from the rotary shaft 101” includes a case that a first axis L1 corresponding to a center axis of the drive rotor 111 is inclined with respect to a second axis L2 corresponding to a center axis of the rotary shaft 101, and a case that the first axis L1 is displaced from the second axis L2 in a state in which the first axis L1 is in parallel to the second axis L2.
However, if a degree at which the drive rotor 111 is deviated from the rotary shaft 101 is increased, an excessive looseness in the clutch 105 tends to be increased, and the vibration and the noise of the motor apparatus tend to be increased.